natcap.invest.sdr.sdr

InVEST Sediment Delivery Ratio (SDR) module.

The SDR method in this model is based on:

Winchell, M. F., et al. “Extension and validation of a geographic information system-based method for calculating the Revised Universal Soil Loss Equation length-slope factor for erosion risk assessments in large watersheds.” Journal of Soil and Water Conservation 63.3 (2008): 105-111.

natcap.invest.sdr.sdr.add_drainage_op(stream, drainage)

raster_map equation: add drainage mask to stream layer.

Parameters:

  • stream (numpy.array) – binary array where 1 indicates a stream, and 0 is a valid landscape pixel but not a stream.

  • drainage (numpy.array) – binary array where 1 indicates any water reaching that pixel drains to a stream.

Returns:

numpy.array combination of stream and drainage

natcap.invest.sdr.sdr.execute(args)

Sediment Delivery Ratio.

This function calculates the sediment export and retention of a landscape using the sediment delivery ratio model described in the InVEST user’s guide.

Parameters:

  • args['workspace_dir'] (string) – output directory for intermediate, temporary, and final files

  • args['results_suffix'] (string) – (optional) string to append to any output file names

  • args['dem_path'] (string) – path to a digital elevation raster

  • args['erosivity_path'] (string) – path to rainfall erosivity index raster

  • args['erodibility_path'] (string) – a path to soil erodibility raster

  • args['lulc_path'] (string) – path to land use/land cover raster

  • args['watersheds_path'] (string) – path to vector of the watersheds

  • args['biophysical_table_path'] (string) – path to CSV file with biophysical information of each land use classes. contain the fields ‘usle_c’ and ‘usle_p’

  • args['threshold_flow_accumulation'] (number) – number of upslope pixels on the dem to threshold to a stream.

  • args['k_param'] (number) – k calibration parameter

  • args['sdr_max'] (number) – max value the SDR

  • args['ic_0_param'] (number) – ic_0 calibration parameter

  • args['drainage_path'] (string) – (optional) path to drainage raster that is used to add additional drainage areas to the internally calculated stream layer

  • args['l_max'] (number) – the maximum allowed value of the slope length parameter (L) in the LS factor. If the calculated value of L exceeds ‘l_max’ it will be clamped to this value.

  • args['n_workers'] (int) – if present, indicates how many worker processes should be used in parallel processing. -1 indicates single process mode, 0 is single process but non-blocking mode, and >= 1 is number of processes.

Returns:

None.

natcap.invest.sdr.sdr.inverse_ws_op(w_factor, s_factor)
natcap.invest.sdr.sdr.threshold_slope_op(slope)

raster_map equation: convert slope to m/m and clamp at 0.005 and 1.0.

As desribed in Cavalli et al., 2013.

natcap.invest.sdr.sdr.usle_op(rkls, cp_factor)